Piezoelectric elements are widely used in a variety of electronic components including ceramic resonators, ceramic filters, piezoelectric displacement elements, buzzers, transducers, ultrasonic receivers and ultrasonic generators, etc. As a result of the increased demand for piezoelectric elements, there is an increasing use of piezoelectric ceramic compositions to form the elements. There is a drive towards increasingly smaller electronic components, causing an increased demand for smaller piezoelectric elements for use in these electronic components.
However, many of the smaller electronic components require that the piezoelectric elements provide the same or even greater output power, despite their reduced size. The different uses or applications require different electromechanical characteristics from the piezoelectric ceramics. In order for piezoelectric ceramic elements to be used in high power applications, they must exhibit certain characteristics, including high mechanical quality factor (Qm), a high relative dielectric constant (∈), and a high coercive field (Ec). Additionally, the dielectric loss factor (tan δ) must be sufficiently low to minimize internal heating effects.
Existing high power piezoelectric ceramics often do not exhibit suitable electromechanical properties for use in miniaturized electronic devices. In the current state of the art, the existing piezoelectric elements that are sufficiently small to be used in the miniaturized devices exhibit low capacitance and high electrical impedance. This is inadequate to drive the miniaturized devices. Additionally, if the permittivity is high, the dielectric loss factor (tan δ) of current piezoelectric elements is also high—resulting in internal heating and dissipative loss which significantly decreases the efficiency and output of the device. Consequently, existing piezoelectric ceramics have not provided adequate electromechanical properties for these miniaturized electronic devices.
The electromechanical properties of the piezoelectric ceramics can be altered by varying the specific ceramic composition, the molecular structure, and/or the methods and parameters for fabricating the piezoelectric ceramic.
In light of the above problems, there is a continuing need for advances in the relevant field including new piezoelectric ceramic compositions and piezoelectric elements formed from the compositions. The present invention addresses that need and provides a wide variety of benefits and advantages.